1. Field of the Invention
The present invention relates to a suction device which is used with a power drilling tool for aspirating material removable during operation of the drilling tool such as drilling dust and drillings and which includes a suction head having a suction opening and displaceable relative to the drilling tool in a direction opposite a drilling direction of the drilling tool, an aeration device for producing a suction air current, and a suction conduit for connecting the suction head with the aeration device.
2. Description of the Prior Art
The advantage of the suction devices of the type described above consists in that a suction nozzle, which forms part of the suction head and is displaceably supported on the drilling tool, is displaced during the drilling process, in the direction opposite the drilling direction by the same amount the drill penetrates into the drilled surface. As a result of the displacement of the suction nozzle, it is always retained at the drill opening, which permits the removal of a relatively large amount of the drilling dust and drillings. The displacement of the suction nozzle relative to the drilling tool is effected by placing the nozzle against the drilling surface, with the nozzle being displaced by the counter-pressure of the surface which is applied to the suction nozzle as the drill advances.
U.S. Pat. No. 5,090,499 discloses a suction device releaseably connectable with a drilling tool. This suction device has an auxiliary handle on which all of the components of the suction device are supported and which can be clamped on the cylindrical receiving surface of the tool to which a conventional auxiliary handle is usually clamped. In order to be able to displace the suction head relative to the drilling tool in the direction opposite the drilling direction during operation of the tool, the suction head is displaceably supported by a rigid section of the suction conduit on the auxiliary handle and is connected with the aeration device by a flexible, bent section of the conduit. The suction conduit is connected at the end of the flexible section remote from the nozzle by the aeration device with a connector of a collection device which is likewise provided on the auxiliary handle.
The drawback of the known suction device is that the suction path between the suction nozzle and the collection device is relatively long because of the flexible bent section of the suction conduit. This leads to relatively high flow losses and a resulting reduction of the suction capacity. Moreover, the drawback of the flexible, bent section of the suction conduit consists in that, on the one hand, flow characteristics change during the drilling operation and, on the other hand, disturbances in the operation of the suction device can occur because of possible bending of the flexible section during operation.
Accordingly, one object of the present invention is to provide a suction device of a type described above in which the drawbacks of the known suction device are eliminated.
Another object of the invention is to provide a suction device of a type described above and having a high suction capacity.